Graphite heating tube and cooking device

Abstract

A graphite heating tube and a cooking device. The graphite heating tube comprises: a hollow tube body (10), the tube body having at least one bent portion (11), the bent portion being formed into a circular arc shape, and defining that a reference line passes through the center of a circle of the bent portion and is perpendicular to the radial direction of the bent portion; and a heating member (20), the heating member being formed into a flake-shaped graphite material member, the heating member passing through the tube body, and in the thickness direction of the heating member, the heating member having a neutral surface (F1) in the center, wherein the neutral surface extends in the length direction of the tube body, and the portion of the neutral surface at least directly facing the bent portion is parallel to the reference line.

Description

Graphite heating tubes and cooking equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application "Graphite heating tube and cooking equipment" with application number: 202311793122.6 and application date of December 22, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present application relates to the technical field of cooking devices, and in particular to a graphite heating tube and cooking equipment. Background Art

[0004] In the related art, graphite heating tubes are made by vacuum-sealing graphite sheets into quartz tubes. However, the graphite sheets are relatively thin, and are prone to distortion and cracking when inserted into the curved quartz tube, resulting in a high defect rate.

[0005] Summary of the Invention

[0006] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a graphite heating tube to improve the yield rate.

[0007] According to the graphite heating tube of the embodiment of the present application, it includes: a hollow tube body, the tube body having at least one bending portion, the bending portion being formed in an arc shape, and a reference line being defined passing through the center of the bending portion and being arranged perpendicular to the radius direction of the bending portion; a heating element, the heating element being formed as a sheet of graphene material, the heating element being passed through the tube body, and having a neutral plane located in the center in the thickness direction of the heating element, the neutral plane extending along the length direction of the tube body, and at least the portion of the neutral plane facing the bending portion being arranged parallel to the reference line.

[0008] According to the graphite heating tube of the embodiment of the present application, by setting at least the portion of the neutral surface opposite to the bent portion parallel to the reference line, the heating element will not be distorted by external forces, so that the heating element can smoothly penetrate into the tube body, thereby improving the yield rate, greatly improving production efficiency, and saving costs.

[0009] Optionally, the curvature radius of the central axis of the bending portion is R1, the curvature radius of a portion of the neutral plane directly opposite to the bending portion is R2, and 0.95≤(R2 / R1)≤1.05.

[0010] Optionally, the heating element includes a plurality of heating units sequentially arranged along the length direction, each of the heating units is formed as a curved section with an opening facing the first direction, and adjacent heating units are connected by a connecting piece.

[0011] Optionally, the connecting piece is connected to the end of the curved section.

[0012] Optionally, each of the heating units includes two parallel heating side walls, the spacing between the two heating side walls is a first spacing, the gap between adjacent heating units is a second spacing, and the first spacing and the second spacing are the same.

[0013] Optionally, the first spacing is 0.5 mm, and the thickness of the heating element is in the range of [0.1 mm, 0.3 mm].

[0014] Optionally, the thickness of the heating element is 0.2 mm.

[0015] Optionally, the tube body is a circular tube.

[0016] Optionally, both ends of the heating element in the longitudinal direction are connected to connecting terminals, each of the connecting terminals is press-sealed and fixed to the tube body, and a portion of the connecting terminal extends out of the tube body.

[0017] Optionally, the connecting terminal includes a main body and a packaging part, the main body is connected to the heating element, the packaging part is connected to the main body and is sealed and fixed to the tube body, and the main body and the packaging part have an angle.

[0018] Optionally, the main body and the packaging part are arranged vertically.

[0019] The cooking device according to the embodiment of the present application includes the above-mentioned graphite heating tube.

[0020] According to the cooking device of the embodiment of the present application, at least the portion of the neutral surface opposite to the bending portion is set parallel to the reference line, so that the heating element will not be distorted by external force, and the heating element can smoothly penetrate into the tube body, thereby improving the yield rate, greatly improving production efficiency, and saving costs.

[0021] Optionally, the cooking device includes: a box body, a pull-out opening is provided on the front side of the box body; a pull-out piece for holding food, the pull-out piece can be pulled out relative to the box body through the pull-out opening; and a graphite heating tube, the graphite heating tube is provided in the box body to heat the inside of the box body.

[0022] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0024] FIG1 is a schematic diagram of a graphite heating tube in a first embodiment of the present application, wherein the graphite heating tube is in a state ready for compression sealing;

[0025] FIG2 is a schematic diagram of the tube body after compression sealing in the first embodiment of the present application, wherein the tube body is partially cut away;

[0026] FIG3 is a schematic diagram of the curvature of the central axis of each part of the tube body in an embodiment of the present application;

[0027] FIG4 is a schematic structural diagram of a heating element in an embodiment of the present application;

[0028] FIG5 is a partial enlarged view of point I in FIG4;

[0029] FIG6 is a schematic diagram of a sweep path formed after the heating element is positioned within the tube body in an embodiment of the present application;

[0030] FIG7 is a first schematic diagram of the cooperation between the heating element and the annular tube in an embodiment of the present application;

[0031] FIG8 is a partial enlarged view of point II in FIG7;

[0032] FIG9 is a first schematic diagram of the cooperation between the heating element and the U-shaped tube in an embodiment of the present application;

[0033] FIG10 is a partial enlarged view of point III in FIG9;

[0034] FIG11 is a first schematic diagram of the cooperation between the heating element and the S-shaped tube in an embodiment of the present application;

[0035] FIG12 is a partial enlarged view of point IV in FIG11;

[0036] FIG13 is an exploded view of a graphite heating tube according to an embodiment of the present application;

[0037] FIG14 is a schematic diagram of a graphite heating tube in a second embodiment of the present application, wherein the graphite heating tube is in a state ready for compression sealing;

[0038] FIG15 is a schematic diagram of the graphite heating tube after compression sealing in the second embodiment of the present application, wherein the tube body is partially cut away;

[0039] FIG16 is a schematic diagram of the angle θ in an embodiment of the present application;

[0040] FIG17 is a schematic diagram of the cooperation between the heating element and the straight tube in an embodiment of the present application;

[0041] FIG18 is a partial enlarged view of point V in FIG17;

[0042] FIG19 is a second schematic diagram of the cooperation between the heating element and the annular tube in an embodiment of the present application;

[0043] FIG20 is a third schematic diagram of the cooperation between the heating element and the annular tube in an embodiment of the present application;

[0044] FIG21 is a second schematic diagram of the cooperation between the heating element and the U-shaped tube in an embodiment of the present application;

[0045] FIG22 is a third schematic diagram of the cooperation between the heating element and the U-shaped tube in an embodiment of the present application;

[0046] FIG23 is a second schematic diagram of the cooperation between the heating element and the S-shaped tube in an embodiment of the present application;

[0047] FIG24 is a third schematic diagram of the cooperation between the heating element and the S-shaped tube in an embodiment of the present application.

[0048] Figure numerals: 100, graphite heating tube; 10, tube body; 11, bending portion; 20, heating element; 22, heating unit; 221, heating side wall; 23, connecting terminal; 231, main body; 232, packaging portion; F1, neutral plane; F2, pressing block; L1, first distance; L2, second distance. DETAILED DESCRIPTION

[0049] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0050] The graphite heating tube 100 according to an embodiment of the present application will be described below with reference to the accompanying drawings.

[0051] As shown in FIG. 1 , according to the graphite heating tube 100 of the embodiment of the present application, the graphite heating tube 100 includes: a tube body 10 and a heating element 20 .

[0052] The tube body 10 is hollow and has at least one bending portion 11 . The bending portion 11 is formed in an arc shape. A reference line is defined passing through the center of the bending portion 11 and is perpendicular to the radius of the bending portion 11 .

[0053] The reference line is a virtual line. This application defines the reference line as a virtual line that passes through the center of the bending portion 11 and is perpendicular to the radius direction of the bending portion 11 of the tube body 10 .

[0054] Specifically, the tube body 10 has at least one bending portion 11, and the bending portion 11 is formed in an arc shape. For example, the overall appearance of the tube body 10 is U-shaped, and the middle part of the U-shaped tube is the arc-shaped bending portion 11; or, the overall appearance of the tube body 10 is S-shaped, and multiple parts of the S-shaped tube are arc-shaped; or, the overall appearance of the tube body 10 is ring-shaped, and each part of the ring-shaped tube is arc-shaped.

[0055] The heating element 20 is formed as a sheet of graphene material. The heating element 20 is inserted into the tube body 10. In the thickness direction of the heating element 20, the heating element 20 has a neutral plane F1 located in the center. The neutral plane F1 extends along the length direction of the tube body 10. At least the part of the neutral plane F1 that is opposite to the bending portion 11 is arranged parallel to the reference line.

[0056] Among them, the graphene material itself has excellent thermal conductivity and heat dissipation capabilities. The graphite heating tube 100 of the present application utilizes the capabilities of the graphene material, so that the graphite heating tube 100 has the advantages of fast heating speed and strong radiation.

[0057] The neutral plane F1 is a virtual plane. This application defines the neutral plane F1 as a virtual plane located at the center of the heating element 20 in the thickness direction and extending along the length direction of the tube body 10 .

[0058] In the related art, graphite heating tubes are made by vacuum-sealing graphite sheets into quartz tubes. However, the graphite sheets are relatively thin, and are prone to distortion and cracking when inserted into the curved quartz tube, resulting in a high defect rate.

[0059] The present application sets at least the portion of the neutral plane F1 that is opposite to the bending portion 11 to be parallel to the reference line, so that the heating element 20 will not be distorted by external forces, and the heating element 20 can smoothly penetrate into the tube body 10, thereby improving the yield rate, greatly improving production efficiency, and saving costs.

[0060] According to the graphite heating tube 100 of the embodiment of the present application, at least the portion of the neutral plane F1 that is opposite to the bent portion 11 is arranged parallel to the reference line, so that the heating element 20 will not be distorted by external forces, and the heating element 20 can smoothly penetrate into the tube body 10, thereby improving the yield rate, greatly improving production efficiency, and saving costs.

[0061] Optionally, the radius of curvature of the central axis of the bend 11 is R1, the radius of curvature of the portion of the neutral plane F1 directly opposite the bend 11 is R2, and 0.95≤(R2 / R1)≤1.05. Based on years of experience and extensive data analysis, the inventors have determined that setting 0.95≤(R2 / R1)≤1.05 further allows the heater 20 to smoothly penetrate the hollow tube 10 without stretching, twisting, or bending, thereby improving product yield.

[0062] Specifically, R1 is the curvature radius of the central axis of the bending portion 11. It should be noted that the central axis of the bending portion 11 is different from the bending portion 11. The bending portion 11 is formed in an arc shape. The bending portion 11 is a component with a certain volume. The part of the bending portion 11 close to the center of the circle and the part away from the center of the circle have different curvature radii. Here, the central axis is a virtual line, and the curvature radius of the central axis is different from the curvature radius of other parts on the bending portion 11.

[0063] Among them, the curvature radius of the part of the neutral plane F1 set opposite to the bending part 11 in this application has a certain correlation with the curvature radius of the central axis of the bending part 11, that is, the part of the neutral plane F1 located in the bending part 11 has a certain correlation with the central axis of the bending part 11, 0.95≤(R2 / R1)≤1.05, so that the heating element 20 is close to the central axis of the bending part 11 in the bending part 11, so that the heating element 20 will not be excessively bent, thereby reducing the probability of the heating element 20 being stretched, twisted and bent.

[0064] For example, R2 / R1 is 1, that is, the central axis of the bending portion 11 is located within the neutral plane F1 of the heating element 20, and the heating element 20 maintains a certain distance from the inner wall of the tube body 10, thereby reducing the probability of the heating element 20 being stretched, twisted, bent, and the like; or, R2 / R1 is 0.95; or, R2 / R1 is 0.97; or, R2 / R1 is 1.02; or, R2 / R1 is 1.05.

[0065] Specifically, in the related art, when packaging graphite heating tubes, a graphite sheet with connecting terminals at both ends is first inserted into a quartz tube. The ends of the quartz tube are heated and melted, then pressed into blocks. After cooling, the graphite sheet and the quartz tube are compressed and sealed together. The graphite sheet is sheet-shaped and the space it occupies is a plane. When inserted into the quartz tube, it can be positioned in any position relative to the swept neutral plane of the quartz tube. Because the graphite sheet is extremely thin, the positioning state formed by the graphite sheet when inserted into the quartz tube and the resulting packaging process parameters directly determine the qualified rate of graphite heating tube manufacturing.

[0066] The curved quartz tube, as the outer protective cover of the graphite heating tube, is also designed into different shapes according to the spatial position of the product. The curved shapes include circular, U-shaped, and S-shaped. As shown in Figures 2 and 3, the sweep centerline of the quartz tube is positioned in the XOY plane coordinate system to form the function relationship of the sweep centerline y1 = f(x). The calculation formula for the curvature radius is as follows:

[0067] Where y· is d(y) / d(x), y·· is d 2 (y) / d(x 2), the function relationship of the swept center line of the quartz tube is substituted into the curvature radius calculation formula to obtain the curvature radius ρa of the swept center line of the quartz tube. The curved quartz tube is generally composed of several arc segments. It is assumed that the curvature radius of each segment is ρa1, ρa2 and ρa3, etc. Specifically, the curvature radius formula is common knowledge and will not be repeated here.

[0068] Before the graphite sheet is introduced into the quartz tube for pressure sealing and melting, the graphite sheet is positioned after entering the quartz tube. As shown in Figures 4, 5, and 6, the sweep centerline of the positioned graphite sheet is also located in the XOY plane coordinate system, forming the functional relationship y2 = f(x) for the sweep centerline of the graphite sheet. Substituting this functional relationship into the curvature radius calculation formula yields the curvature radius ρb of the sweep centerline of the graphite sheet, as well as the curvature radii ρb1, ρb2, and ρb3 of the sweep path of the graphite sheet after positioning in the curved quartz tube. Therefore, the curvature radius ratio λ = ρb / ρa of the graphite sheet and quartz tube in each segment is calculated. The curvature radius ratio λ is R2 / R1.

[0069] The present application proposes that R2 / R1 is within the range of 0.95 to 1.05, and that the bending direction of the heating element 20 is consistent with the bending direction of the tube body 10, thereby forming the optimal process parameters for the positioning relationship between the heating element 20 and the tube body 10. Under the optimal parameters, the heating element 20 can smoothly penetrate into various curved tubes, especially annular tubes, U-shaped tubes and S-shaped tubes.

[0070] Specifically, by positioning the annular tube according to the optimal position relationship process parameters proposed in this application, an annular tube as shown in Figures 7 and 8 can be successfully obtained. After the heating element 20 is encapsulated into the tube body 10, a partial enlarged view of the heating element 20 shows that the offset angle between the heating element 20 and the sweeping plane is less than 5°, which makes it difficult for the heating element 20 to come into contact with the inner wall of the tube body 10. At the same time, the various teeth of the heating element 20 are evenly distributed, and are not prone to stretching, twisting, and bending. After the melt pressing is cooled, cracks are rarely found in the heating element 20.

[0071] Specifically, the U-shaped tube was positioned according to the optimal position relationship process parameters proposed in this application, resulting in the U-shaped tube shown in Figures 9 and 10. The teeth of the heating element 20 were evenly distributed, and the offset angle of the heating element 20 was less than 5°. After forming, the heating element 20 rarely had defects such as cracks, excessive stretching, twisting, and bending.

[0072] Specifically, the S-shaped tube was positioned according to the process parameters of the present application to obtain the S-shaped tube shown in Figures 11 and 12. It can also be seen that the teeth of the heating element 20 are very evenly distributed, without any localized large stretching, twisting, or bending, and no cracked graphite sheets were observed after forming.

[0073] By positioning the heating element 20 to various curved tube body positions according to the present application, optimal positioning process parameters are formed. This allows the heating element 20 to easily penetrate the tube body 10, and rarely finds heating elements 20 damaged by stretching, twisting, bending, etc., thus ensuring the integrity and reliability of the packaged heating element 20. Through the process of the present application, the qualified rate of the packaging manufacturing of the heating element 20 has been increased by more than 23%, which has greatly improved the production efficiency of the graphite heating tube 100, provided the best process guarantee for the mass production and high qualified rate of the graphite heating tube 100, and saved considerable manufacturing costs.

[0074] As shown in Figures 4 and 5, the heating element 20 optionally includes a plurality of heating units 22 arranged sequentially along the length direction. Each heating unit 22 is formed as a curved section with an opening facing the first direction, and adjacent heating units 22 are connected by connecting pieces. Heating by the plurality of heating units 22 arranged sequentially along the length direction allows the heating element 20 to dissipate heat sufficiently, thereby improving the heating efficiency of the graphite heating tube 100. The first direction is a manually set direction, which can be specifically upward, downward, leftward, or rightward.

[0075] Specifically, the heating unit 22 is formed as a curved section with an opening toward the first direction. The heating element 20 includes a plurality of heating units 22, and the heating units 22 are connected by connecting plates, that is, the structure of the heating element 20 is: a circulation structure of heating unit 22 + connecting plate + heating unit 22. Of course, it can also be a circulation structure of connecting plate + heating unit 22 + connecting plate.

[0076] Optionally, the connecting piece is connected to the middle part of the curved section, that is, the curved section is partially suspended, thereby improving the heating efficiency.

[0077] In other embodiments, the connecting piece is connected to the end of the curved section. By providing the connecting piece to be connected to the end of the curved section, the probability of the heating element 20 contacting the inner wall of the tube body 10 is reduced.

[0078] As shown in Figures 4 and 5, each heating unit 22 optionally includes two parallel heating side walls 221. The spacing between the two heating side walls 221 is a first spacing L1, and the spacing between adjacent heating units 22 is a second spacing L2. The first spacing L1 and the second spacing L2 are equal. By setting the first spacing L1 between the two heating side walls 221 to be equal to the second spacing L2 between adjacent heating units 22, the heating element 20 is heated evenly, and the heat around the heating element 20 is uniform, thereby improving heating uniformity.

[0079] Each heating unit 22 includes two parallel heating side walls 221 . Heat is generated by the two heating side walls 221 , and the heated surface receives more energy, thereby increasing the heating speed.

[0080] Specifically, the two heating side walls 221 are spaced apart by a first distance L1, and the two heating side walls 221 heat the surrounding air. The two adjacent heating units 22 are spaced apart by a second distance L2, and the heating side walls 221 of the two adjacent heating units 22 have the same influence range, so that the heating element 20 is heated evenly.

[0081] Optionally, the first spacing L1 is 0.5 mm, and the thickness of the heating element 20 ranges from 0.1 mm to 0.3 mm. By setting the thickness of the heating element 20 with a first spacing L1 of 0.5 mm to a range of 0.1 mm to 0.3 mm, the heating element 20 meets both strength and manufacturing process yield requirements.

[0082] After a large number of experimental investigations, the inventors of the present application found that: graphene material is a brittle material. Usually, the elastic modulus of the graphite sheet of graphene material is very small. Therefore, it is easy to cause the graphite sheet to break when it is pulled during the installation process or the thermal shock load of 1000 degrees when it is powered on and heated after installation, resulting in failure of the heating tube. According to the calculation formula of the elastic modulus of elastic material, the strength of the material itself can be improved by increasing the thickness of the material. However, increasing the thickness of the material also has the problem of manufacturing process. The relevant process for manufacturing graphite sheet is to press the graphene material of porous medium material into sheet material by physical pressing, and then use the die to shear the shape shown in Figure 5. In this process, after the thickness of the graphite sheet increases to a certain extent, the shear stress of the cross section will decrease accordingly during the die shearing process. Therefore, it is easy for the graphite materials to stick together during the cutting process, which leads to burrs on the finished product after cutting, resulting in the production of defective products. In terms of this issue, the thickness of the graphene material has always been a contradiction.

[0083] In terms of manufacturing process, in order to quickly cut the graphite sheet and reduce burrs, the overall shear stress range should be greater than 4 MPa. In order to ensure that it is not damaged during actual working conditions, the tensile strength of the graphite sheet should be greater than 3.5 MPa. After a large number of simulations and experimental studies, the inventors of this application found that when the cutting distance is 0.5 mm, when the thickness is in the range of [0.1 mm, 0.3 mm], the strength and manufacturing process requirements can be met at the same time.

[0084] Specifically: the thickness of the 0.5mm spacing cut graphite sheet is 0.1mm, the tensile strength is 3.5MPa, and the shear stress is 15MPa; the thickness of the 0.5mm spacing cut graphite sheet is 0.2mm, the tensile strength is 7.3MPa, and the shear stress is 9.8MPa; the thickness of the 0.5mm spacing cut graphite sheet is 0.3mm, the tensile strength is 10.7MPa, and the shear stress is 4.3MPa.

[0085] For example, the thickness of the heating element 20 is 0.1 mm; or, the thickness of the heating element 20 is 0.15 mm; or, the thickness of the heating element 20 is 0.2 mm; or, the thickness of the heating element 20 is 0.25 mm; or, the thickness of the heating element 20 is 0.3 mm.

[0086] Specifically, the thickness of the heating element 20 is 0.2 mm. By setting the thickness to 0.2 mm, a margin of nearly 1 times is retained for both shear stress and tensile strength at this thickness, thereby improving the overall reliability.

[0087] Optionally, the tube body 10 is a circular tube. By configuring the tube body 10 as a circular tube, it is convenient to package the heating element 20 into the tube body 10, reducing the probability of damage during the compression sealing process and further improving the yield rate.

[0088] Specifically, the cross section of the circular tube is circular. When the heating element 20 penetrates the circular tube, the distances between the heating element 20 and various parts of the inner wall of the circular tube are similar, so that the heating element 20 is easier to control.

[0089] In other embodiments, the tube body 10 is a prismatic tube. Specifically, the cross section of the prismatic tube is a prismatic tube.

[0090] As shown in Figures 4 and 13, optionally, connecting terminals 23 are connected to both ends of the length direction of the heating element 20. Each connecting terminal 23 is press-sealed and fixed to the tube body 10, and a portion of the connecting terminal 23 extends out of the tube body 10. By providing the connecting terminals 23 and the tube body 10 with press-sealed and fixed, the heating element 20 is stabilized within the tube body 10.

[0091] Specifically, the compression sealing process is as follows: First, the heater is gently inserted into the tube, ensuring the appropriate amount of extension of the connecting terminals. Then, through methods such as flame heating, the ends of the tube are heated to a molten state. The compression blocks on both sides of the tube are then automatically and rapidly closed, squeezing the molten tube. Once the tube cools, the connecting terminals and the tube are compressed and sealed together, ultimately creating a vacuum seal, completing the process of encapsulating the heater into the tube.

[0092] Optionally, the connecting terminal 23 includes a main portion 231 and a packaging portion 232. The main portion 231 is connected to the heating element 20, and the packaging portion 232 is connected to the main portion 231 and is press-sealed and fixed to the tube body 10. The main portion 231 and the packaging portion 232 form an angle. By setting the angle between the main portion 231 and the packaging portion 232, the probability of problems such as air leakage from the graphite heating tube 100 and cracks in the heating element 20 and the connecting terminal 23 during the press-sealing and fixing of the connecting terminal 23 to the tube body 10 is reduced.

[0093] In the related art, when encapsulating a graphite sheet into a quartz tube, the sheet is inserted into the tube relatively randomly. As the tube cools and solidifies, the graphite sheet is subjected to stress, which may cause the sheet to deform and twist, or it may be squeezed against the inner wall of the tube. Various situations may cause cracks in the graphite sheet, resulting in a low pass rate. The present application provides an angle between the main body 231 and the packaging portion 232. This angle is pre-set between the main body 231 and the packaging portion 232 to improve deformation of the heating element 20 during the cooling and solidification of the tube body 10, reduce the probability of cracks, and improve the packaging manufacturing pass rate.

[0094] Optionally, the angle θ between the main body 231 and the sealing portion 232 is 180°. Specifically, the tube body 10 is a straight tube, as shown in Figures 13 and 16 , with the angle θ being 180°. During parallel sealing, the graphite sheet is parallel to the sealing plane, preventing stretching and distortion during insertion. Furthermore, during melt sealing, the terminals at both ends are unlikely to form an uneven shape with the sealing plane, thereby reducing cracks in the terminals and air leakage from the sealed tube head.

[0095] Optionally, the main body 231 and the packaging portion 232 are arranged perpendicularly. By arranging the main body 231 and the packaging portion 232 perpendicularly, the heating element 20 can be easily inserted into the tube body 10, and it is not easy to cause stretching, twisting, bending, etc. to damage the sheet-shaped heating element 20, thereby ensuring the integrity of the packaged heating element 20; at the same time, during the melt-sealing process, the connecting terminal 23 and the tube head of the tube body 10 can be kept parallel, greatly reducing cracks in the connecting terminal 23 and air leakage in the tube head.

[0096] For example, the tube body 10 is a straight tube, and the heater 20 of the straight tube is shown in Figures 17 and 18. The angle θ is 90°. Before gently inserting the graphite sheet, the terminals at both ends are twisted 90°. This ensures that the neutral plane of the inserted graphite sheet is perpendicular to the neutral plane of the quartz tube head to be formed, and the terminals are parallel to the tube head pressure surface. This vertical packaging of the straight tube is less likely to cause cracks in the terminals and leaks in the tube head, and also prevents stretching and distortion of the graphite sheet.

[0097] Alternatively, the tube body 10 is any one of an annular tube, a U-shaped tube, and an S-shaped tube, and the angle θ is 90°, so that the neutral plane F1 and the neutral plane of the tube head of the tube body 10 are perpendicular. The compression seal packaging of the annular tube is shown in Figures 19 and 20. When the heating element 20 is inserted into the annular tube, this vertical state and the angle θ of 90° allow the heating element 20 to easily penetrate along the neutral plane of the annular tube, and the heating element 20 is not easily stretched or twisted. When the connecting terminal 23 is melted and compressed, it can also better maintain parallelism with the compression seal of the tube head of the tube body 10, reducing the generation of cracks in the connecting terminal 23 and air leakage from the compression seal head. The compression seal packaging of the U-shaped tube is shown in Figures 21 and 22. Similar to the annular tube, it can also ensure that the heating element 20 can easily pass through the semicircle, ensuring the manufacturing qualification rate during insertion and packaging. The pressure-sealed package of the S-shaped tube is shown in Figures 23 and 24. Similar to the annular tube and the U-shaped tube, when the heating element 20 passes through the upper bending portion 11 of the tube body 10, it is not easy to be stretched or twisted. At the same time, when the connecting terminal 23 is melted and pressure-sealed, there is rarely leakage or cracking of the tube head.

[0098] Specifically, the probabilities of various problems occurring in the circular tube of C-1 before process improvement were as follows: graphite flake film breakage 1.13%, graphite flake strain 3.62%, graphite flake sprain 2.83%, graphite flake crease 5.51%, molybdenum flake cracking 6.82%, molybdenum flake wrinkling 6.78%, pressure-sealed bubbles 7.58%, pressure-sealed air leakage 5.31%, and a total of 39.58%; after process improvement, the probabilities of various problems occurring in the circular tube of C-1 were as follows: graphite flake film breakage 0.54%, graphite flake strain 1.45%, graphite flake sprain 2.13%, graphite flake crease 2.55%, molybdenum flake cracking 1.97%, molybdenum flake wrinkling 2.96%, pressure-sealed bubbles 2.65%, pressure-sealed air leakage 1.62%, and a total of 15.87%. The qualified rate before and after improvement was improved by 23.7%.

[0099] Specifically, the probabilities of various problems occurring in the circular tube of C-2 before process improvement were as follows: graphite flake film breakage 1.15%, graphite sheet strain 3.11%, graphite sheet sprain 2.65%, graphite sheet crease 5.16%, molybdenum sheet cracking 6.95%, molybdenum sheet wrinkling 6.12%, pressure-sealed bubbles 7.74%, pressure-sealed air leakage 5.46%, and a total of 38.34%; after process improvement, the probabilities of various problems occurring in the circular tube of C-2 were as follows: graphite flake film breakage 0.52%, graphite sheet strain 1.41%, graphite sheet sprain 2.15%, graphite sheet crease 2.52%, molybdenum sheet cracking 1.82%, molybdenum sheet wrinkling 2.84%, pressure-sealed bubbles 2.53%, pressure-sealed air leakage 1.56%, and a total of 15.35%. The qualified rate was improved by 23.0% before and after improvement.

[0100] Specifically, the probabilities of various problems occurring in the U-shaped tube of U-1 before process improvement were as follows: graphite flake film breakage 1.12%, graphite flake strain 3.82%, graphite flake sprain 2.74%, graphite flake crease 5.37%, molybdenum flake cracking 6.72%, molybdenum flake wrinkling 6.25%, pressure-sealed bubbles 7.32%, pressure-sealed air leakage 4.9%, and a total of 38.24%; after process improvement, the probabilities of various problems occurring in the U-shaped tube of U-1 were as follows: graphite flake film breakage 0.52%, graphite flake strain 1.43%, graphite flake sprain 2.16%, graphite flake crease 2.47%, molybdenum flake cracking 1.94%, molybdenum flake wrinkling 2.94%, pressure-sealed bubbles 2.42%, pressure-sealed air leakage 1.51%, and a total of 15.39%. The qualified rate was improved by 22.9% before and after improvement.

[0101] Specifically, the probabilities of various problems occurring in the S-shaped tube of S-1 before process improvement were as follows: graphite flake film breakage 1.10%, graphite flake strain 3.78%, graphite flake sprain 2.81%, graphite flake crease 5.11%, molybdenum flake cracking 6.42%, molybdenum flake wrinkling 6.85%, pressure-sealed bubbles 7.12%, pressure-sealed air leakage 4.77%, and a total of 37.96%; after process improvement, the probabilities were as follows: graphite flake film breakage 0.51%, graphite flake strain 1.46%, graphite flake sprain 2.18%, graphite flake crease 2.49%, molybdenum flake cracking 1.81%, molybdenum flake wrinkling 2.87%, pressure-sealed bubbles 2.42%, pressure-sealed air leakage 1.55%, and a total of 15.29%. The qualified rate before and after improvement was improved by 22.7%.

[0102] Specifically, the probabilities of various problems occurring in the S-shaped tube of S-1 before process improvement were as follows: graphite flake film breakage 1.11%, graphite flake strain 3.73%, graphite flake sprain 2.92%, graphite flake crease 5.05%, molybdenum flake cracking 6.38%, molybdenum flake wrinkling 6.81%, pressure-sealed bubbles 7.04%, pressure-sealed air leakage 4.63%, and a total of 37.67%; after process improvement, the probabilities of various problems occurring in the S-shaped tube of S-1 were as follows: graphite flake film breakage 0.58%, graphite flake strain 1.41%, graphite flake sprain 2.20%, graphite flake crease 2.41%, molybdenum flake cracking 1.86%, molybdenum flake wrinkling 2.81%, pressure-sealed bubbles 2.34%, pressure-sealed air leakage 1.48%, and a total of 15.09%. The qualified rate before and after improvement was improved by 22.6%.

[0103] In summary, the defective ratio of graphite heating tubes has dropped significantly, and the overall qualified rate has increased by about 23%.

[0104] A specific embodiment of the graphite heating tube 100 of the present application is described below with reference to FIG. 1 to FIG. 24 .

[0105] A graphite heating tube 100 includes a tube body 10 and a heating element 20 .

[0106] The tube body 10 is a hollow quartz tube. The shape of the tube body 10 is a U-shaped tube. The tube body 10 is a circular tube with a circular cross-section. The tube body 10 has a bending portion 11. The bending portion 11 is formed in an arc shape. The defined reference line passes through the center of the bending portion 11 and is perpendicular to the radius direction of the bending portion 11.

[0107] The heating element 20 is a sheet of graphene material, inserted into the tube body 10. It comprises a plurality of heating units 22 arranged sequentially along the length. Each heating unit 22 is formed as a curved segment with its opening facing in the first direction. Adjacent heating units 22 are connected by a connecting piece, which is connected to the end of the curved segment. Each heating unit 22 includes two parallel heating side walls 221. The spacing between the two heating side walls 221 is a first spacing L1, and the gap between adjacent heating units 22 is a second spacing L2. The first spacing L1 and the second spacing L2 are equal. The first spacing L1 is 0.5 mm, and the thickness of the heating element 20 is 0.2 mm.

[0108] Connecting terminals 23 are connected to both ends of the heating element 20 in the longitudinal direction. Each connecting terminal 23 is press-sealed and fixed to the tube body 10, and a portion of the connecting terminal 23 extends out of the tube body 10. The connecting terminal 23 includes a main body 231 and a packaging portion 232. The main body 231 is connected to the heating element 20, and the packaging portion 232 is connected to the main body 231 and press-sealed and fixed to the tube body 10. The main body 231 and the packaging portion 232 are arranged vertically.

[0109] The heating element 20 has a central neutral plane F1 along its thickness. The neutral plane F1 extends along the length of the tube 10, and at least the portion of the neutral plane F1 directly opposite the bend 11 is parallel to the reference line. The central axis of the bend 11 has a radius of curvature R1, and the portion of the neutral plane F1 directly opposite the bend 11 has a radius of curvature R2, where R2 / R1 equals 1.

[0110] The cooking device according to the embodiment of the present application includes the above-mentioned graphite heating tube 100.

[0111] According to the cooking device of the embodiment of the present application, at least the portion of the neutral plane F1 that is opposite to the bending portion 11 is set parallel to the reference line, so that the heating element 20 will not be distorted by external forces, and the heating element 20 can smoothly penetrate into the tube body 10, thereby improving the yield rate, greatly improving production efficiency, and saving costs.

[0112] Optionally, the cooking device includes: a box body, a drawer and a graphite heating tube 100 .

[0113] A drawer opening is provided on the front side of the box.

[0114] The drawer is used for holding food, and the drawer can be drawn relative to the box body through the drawer opening.

[0115] The graphite heating tube 100 is disposed in the box to heat the interior of the box.

[0116] Among them, the pull-out piece is used to hold food. Compared with the solution in the related art that the food carrying space is fixed in the cooking appliance, this application makes it convenient to place and take out food.

[0117] For example, the cooking device is an oven; or, the cooking device is an air fryer; or, the cooking device is a microwave oven.

[0118] Other structures and operations of the graphite heating tube 100 according to the embodiment of the present application are known to those skilled in the art and will not be described in detail here.

[0119] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0120] In addition, features defined as "first" or "second" may explicitly or implicitly include one or more such features, and are used to distinguish and describe features, without any distinction in order or importance.

[0121] In the description of the present application, unless otherwise specified, “plurality” means two or more.

[0122] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0123] Throughout this specification, references to terms such as "embodiment" and "example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0124] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A graphite heating tube, wherein: include: A hollow tube body, wherein the tube body has at least one bending portion, wherein the bending portion is formed into an arc shape, and a reference line is defined passing through the center of the bending portion and being arranged perpendicular to the radius direction of the bending portion; A heating element, wherein the heating element is formed as a sheet of graphene material, the heating element is inserted into the tube body, and in the thickness direction of the heating element, the heating element has a neutral plane located in the center, the neutral plane extends along the length direction of the tube body, and at least the portion of the neutral plane that is opposite to the bending portion is arranged parallel to the reference line.

2. The graphite heating tube according to claim 1, wherein: The curvature radius of the central axis of the bending portion is R1, the curvature radius of the portion of the neutral plane directly opposite to the bending portion is R2, and 0.95≤(R2 / R1)≤1.

05.

3. The graphite heating tube according to claim 1 or 2, wherein: The heating element comprises a plurality of heating units sequentially arranged along the length direction, each of the heating units is formed as a curved section with an opening facing the first direction, and adjacent heating units are connected via a connecting sheet.

4. The graphite heating tube according to claim 3, wherein: The connecting piece is connected to the end of the curved section.

5. The graphite heating tube according to claim 3 or 4, wherein: Each of the heating units includes two parallel heating side walls, the distance between the two heating side walls is a first distance, the gap between adjacent heating units is a second distance, and the first distance is the same as the second distance.

6. The graphite heating tube according to claim 5, wherein: The first spacing is 0.5 mm, and the thickness of the heating element ranges from [0.1 mm to 0.3 mm].

7. The graphite heating tube according to claim 6, wherein: The thickness of the heating element is 0.2 mm.

8. The graphite heating tube according to any one of claims 1 to 7, wherein: The tube body is a circular tube.

9. The graphite heating tube according to any one of claims 1 to 8, wherein: Both ends of the heating element in the length direction are connected with connecting terminals, each of the connecting terminals is sealed and fixed with the tube body, and a part of the connecting terminal extends out of the tube body.

10. The graphite heating tube according to claim 9, wherein: The connecting terminal comprises a main body and a packaging part, wherein the main body is connected to the heating element, the packaging part is connected to the main body and is sealed and fixed to the tube body, and an angle is formed between the main body and the packaging part.

11. The graphite heating tube according to claim 10, wherein: The main body and the packaging part are vertically arranged.

12. A cooking device, wherein: A graphite heating tube comprising any one of claims 1 to 11.

13. The cooking device according to claim 12, wherein: The cooking device comprises: A box body, wherein a drawer opening is provided on the front side of the box body; A drawer for holding food, the drawer being drawable relative to the box body through the drawer opening; A graphite heating tube is arranged in the box to heat the inside of the box.

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